
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


static ngx_chain_t *ngx_udp_output_chain_to_iovec(ngx_iovec_t *vec,
                                                  ngx_chain_t *in,
                                                  ngx_log_t   *log);
static ssize_t      ngx_sendmsg(ngx_connection_t *c, ngx_iovec_t *vec);


ngx_chain_t *
ngx_udp_unix_sendmsg_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
{
    ssize_t      n;
    off_t        send;
    ngx_chain_t *cl;
    ngx_event_t *wev;
    ngx_iovec_t  vec;
    struct iovec iovs[NGX_IOVS_PREALLOCATE];

    wev = c->write;

    if (!wev->ready)
    {
        return in;
    }

#if (NGX_HAVE_KQUEUE)

    if ((ngx_event_flags & NGX_USE_KQUEUE_EVENT) && wev->pending_eof)
    {
        (void)ngx_connection_error(
            c, wev->kq_errno, "kevent() reported about an closed connection");
        wev->error = 1;
        return NGX_CHAIN_ERROR;
    }

#endif

    /* the maximum limit size is the maximum size_t value - the page size */

    if (limit == 0 || limit > (off_t)(NGX_MAX_SIZE_T_VALUE - ngx_pagesize))
    {
        limit = NGX_MAX_SIZE_T_VALUE - ngx_pagesize;
    }

    send = 0;

    vec.iovs   = iovs;
    vec.nalloc = NGX_IOVS_PREALLOCATE;

    for (;;)
    {
        /* create the iovec and coalesce the neighbouring bufs */

        cl = ngx_udp_output_chain_to_iovec(&vec, in, c->log);

        if (cl == NGX_CHAIN_ERROR)
        {
            return NGX_CHAIN_ERROR;
        }

        if (cl && cl->buf->in_file)
        {
            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                          "file buf in sendmsg "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary, cl->buf->recycled,
                          cl->buf->in_file, cl->buf->start, cl->buf->pos,
                          cl->buf->last, cl->buf->file, cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();

            return NGX_CHAIN_ERROR;
        }

        if (cl == in)
        {
            return in;
        }

        send += vec.size;

        n = ngx_sendmsg(c, &vec);

        if (n == NGX_ERROR)
        {
            return NGX_CHAIN_ERROR;
        }

        if (n == NGX_AGAIN)
        {
            wev->ready = 0;
            return in;
        }

        c->sent += n;

        in = ngx_chain_update_sent(in, n);

        if (send >= limit || in == NULL)
        {
            return in;
        }
    }
}


static ngx_chain_t *
ngx_udp_output_chain_to_iovec(ngx_iovec_t *vec, ngx_chain_t *in, ngx_log_t *log)
{
    size_t        total, size;
    u_char       *prev;
    ngx_uint_t    n, flush;
    ngx_chain_t  *cl;
    struct iovec *iov;

    cl    = in;
    iov   = NULL;
    prev  = NULL;
    total = 0;
    n     = 0;
    flush = 0;

    for (/* void */; in && !flush; in = in->next)
    {
        if (in->buf->flush || in->buf->last_buf)
        {
            flush = 1;
        }

        if (ngx_buf_special(in->buf))
        {
            continue;
        }

        if (in->buf->in_file)
        {
            break;
        }

        if (!ngx_buf_in_memory(in->buf))
        {
            ngx_log_error(NGX_LOG_ALERT, log, 0,
                          "bad buf in output chain "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          in->buf->temporary, in->buf->recycled,
                          in->buf->in_file, in->buf->start, in->buf->pos,
                          in->buf->last, in->buf->file, in->buf->file_pos,
                          in->buf->file_last);

            ngx_debug_point();

            return NGX_CHAIN_ERROR;
        }

        size = in->buf->last - in->buf->pos;

        if (prev == in->buf->pos)
        {
            iov->iov_len += size;
        }
        else
        {
            if (n == vec->nalloc)
            {
                ngx_log_error(NGX_LOG_ALERT, log, 0,
                              "too many parts in a datagram");
                return NGX_CHAIN_ERROR;
            }

            iov = &vec->iovs[n++];

            iov->iov_base = (void *)in->buf->pos;
            iov->iov_len  = size;
        }

        prev = in->buf->pos + size;
        total += size;
    }

    if (!flush)
    {
#if (NGX_SUPPRESS_WARN)
        vec->size  = 0;
        vec->count = 0;
#endif
        return cl;
    }

    vec->count = n;
    vec->size  = total;

    return in;
}


static ssize_t
ngx_sendmsg(ngx_connection_t *c, ngx_iovec_t *vec)
{
    ssize_t       n;
    ngx_err_t     err;
    struct msghdr msg;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)

#if (NGX_HAVE_IP_SENDSRCADDR)
    u_char msg_control[CMSG_SPACE(sizeof(struct in_addr))];
#elif (NGX_HAVE_IP_PKTINFO)
    u_char msg_control[CMSG_SPACE(sizeof(struct in_pktinfo))];
#endif

#if (NGX_HAVE_INET6 && NGX_HAVE_IPV6_RECVPKTINFO)
    u_char msg_control6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
#endif

#endif

    ngx_memzero(&msg, sizeof(struct msghdr));

    if (c->socklen)
    {
        msg.msg_name    = c->sockaddr;
        msg.msg_namelen = c->socklen;
    }

    msg.msg_iov    = vec->iovs;
    msg.msg_iovlen = vec->count;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)

    if (c->listening && c->listening->wildcard && c->local_sockaddr)
    {
#if (NGX_HAVE_IP_SENDSRCADDR)

        if (c->local_sockaddr->sa_family == AF_INET)
        {
            struct cmsghdr     *cmsg;
            struct in_addr     *addr;
            struct sockaddr_in *sin;

            msg.msg_control    = &msg_control;
            msg.msg_controllen = sizeof(msg_control);

            cmsg             = CMSG_FIRSTHDR(&msg);
            cmsg->cmsg_level = IPPROTO_IP;
            cmsg->cmsg_type  = IP_SENDSRCADDR;
            cmsg->cmsg_len   = CMSG_LEN(sizeof(struct in_addr));

            sin = (struct sockaddr_in *)c->local_sockaddr;

            addr  = (struct in_addr *)CMSG_DATA(cmsg);
            *addr = sin->sin_addr;
        }

#elif (NGX_HAVE_IP_PKTINFO)

        if (c->local_sockaddr->sa_family == AF_INET)
        {
            struct cmsghdr     *cmsg;
            struct in_pktinfo  *pkt;
            struct sockaddr_in *sin;

            msg.msg_control    = &msg_control;
            msg.msg_controllen = sizeof(msg_control);

            cmsg             = CMSG_FIRSTHDR(&msg);
            cmsg->cmsg_level = IPPROTO_IP;
            cmsg->cmsg_type  = IP_PKTINFO;
            cmsg->cmsg_len   = CMSG_LEN(sizeof(struct in_pktinfo));

            sin = (struct sockaddr_in *)c->local_sockaddr;

            pkt = (struct in_pktinfo *)CMSG_DATA(cmsg);
            ngx_memzero(pkt, sizeof(struct in_pktinfo));
            pkt->ipi_spec_dst = sin->sin_addr;
        }

#endif

#if (NGX_HAVE_INET6 && NGX_HAVE_IPV6_RECVPKTINFO)

        if (c->local_sockaddr->sa_family == AF_INET6)
        {
            struct cmsghdr      *cmsg;
            struct in6_pktinfo  *pkt6;
            struct sockaddr_in6 *sin6;

            msg.msg_control    = &msg_control6;
            msg.msg_controllen = sizeof(msg_control6);

            cmsg             = CMSG_FIRSTHDR(&msg);
            cmsg->cmsg_level = IPPROTO_IPV6;
            cmsg->cmsg_type  = IPV6_PKTINFO;
            cmsg->cmsg_len   = CMSG_LEN(sizeof(struct in6_pktinfo));

            sin6 = (struct sockaddr_in6 *)c->local_sockaddr;

            pkt6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
            ngx_memzero(pkt6, sizeof(struct in6_pktinfo));
            pkt6->ipi6_addr = sin6->sin6_addr;
        }

#endif
    }

#endif

eintr:

    n = sendmsg(c->fd, &msg, 0);

    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0, "sendmsg: %z of %uz", n,
                   vec->size);

    if (n == -1)
    {
        err = ngx_errno;

        switch (err)
        {
        case NGX_EAGAIN:
            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                           "sendmsg() not ready");
            return NGX_AGAIN;

        case NGX_EINTR:
            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                           "sendmsg() was interrupted");
            goto eintr;

        default:
            c->write->error = 1;
            ngx_connection_error(c, err, "sendmsg() failed");
            return NGX_ERROR;
        }
    }

    return n;
}
